For LOC constraint, there is a SOFT attribute:
INST instance_name LOC=location :location {SOFT };
If SOFT is specified, PAR may place the constraint elsewhere if better results can be obtained at a location outside the bounding box. Examples of LOC constraints used to specify a range are given below.
The SOFT attribute is supported in the ISE design tools, but not in the PlanAhead tool:
CRITICAL WARNING: [Designutils 20-31] Unrecognized symbol SOFT [C:/Project/bft/bft.srcs/constrs_2/imports/Sources/bft_full.ucf:4]
The Soft attribute for LOC will not be available in PlanAhead (or in Vivado XDC). You should use Pblocks to get a "soft LOC" (i.e., range).
In the PlanAhead tool, you could work around this issue by adding the soft LOC to a UCF file, and include the ucf file using the -uc option in the NGDBUILD other command line options.
AR# 52592 | |
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日期 | 11/08/2013 |
状态 | Archive |
Type | 综合文章 |
器件 | |
Tools |